Note: Descriptions are shown in the official language in which they were submitted.
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Device for subjecting probes to irradiation in the core of a heavy water
reactor,
diverter, installation for producing activated probes in the core of a heavy
water
reactor and heavy water reactor
The present invention relates to a device for subjecting probes to irradiation
in the
core of a heavy water nuclear reactor, in particular of a CANDU reactor, a
diverter, an
installation for producing activated probes in the core of the heavy water
reactor and a heavy
water reactor.
Heavy water type nuclear power plants, specifically CANDU pressurized heavy
water
reactors, have a very high thermal neutron flux and a high level epithermal
neutron flux over
a wide range of resonance that is capable of activating non-uranium based
targets with
neutron capture. Such neutron capture considerably reduces the waste created
to obtain
the radioisotopes as well has the capability to produce significant amounts of
radioisotopes
such as Mo-99 or Lu-177 to replace production from aging research reactors as
they are
retired.
Several studies have been done looking at modifying CANDU fuel elements
contained
in the pressure tubes of the primary coolant loop to include irradiation
targets allowing
production of isotopes. This involves using the on-line fueling machines to
insert and
retrieve the modified fuel elements, which creates on operational risk to the
reactor as the
fueling functions place restrictions on the operating units as well may
increase the risk of a
reactor trip due to inadvertent events. The use of modified fuel elements also
requires
substantial changes in the plant design to address the modified fuel element
and getting
the fuel element out of the Spent Fuel Bay for isotope extraction purposes.
WO 2016/207054 Al describes a device for inserting and retrieving targets into
a
heavy water type nuclear power plant comprising a guide tube introduced
through a free
access port allowing access to the core of the nuclear reactor, for example a
view port, the
access port being located in the reactivity mechanism deck of the nuclear
reactor. The guide
tube extends into the moderator of the nuclear reactor, and contains a
plurality of pressure
boundary tubes, intended for receiving the targets in view of their
irradiation in the core of
the nuclear reactor.
This device is, however, not entirely satisfactory. In particular, due in
particular to the
Y-shaped geometry of the distributor, which includes the inlet/outlet for the
targets on one
branch of the Y and the inlet for the gas for pushing the targets out of the
device on the
other branch of the Y, this device only allows for relatively small bending
radii or target
geometries. It is therefore only adapted for receiving spherical targets of
relatively small
diameter. Considering the tight space constraints in this location of the
CANDU reactor, it
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is unlikely that such a design could be used for cylindrical targets having a
larger diameter,
since this would result in considerably larger dimensions of the device. In
addition, the
device described in this document cannot be easily lifted out of the port of
the reactivity
mechanism deck in one piece.
One purpose of the invention is to provide a device which allows for inserting
and
retrieving a larger variety of probes into and from the core of a heavy water
reactor which
is easy to handle and is further compact.
For this purpose, the invention relates to a device for subjecting probes to
irradiation
in the core of a heavy water nuclear reactor, comprising:
- a plurality of probe receiving fingers, each probe receiving finger defining
a
longitudinal axis, and extending into the core of the nuclear reactor,
each probe receiving finger being configured for receiving a plurality of
probes in view
of their irradiation in the core of the nuclear reactor, and
each probe receiving finger having a double walled structure comprising an
inner tube
and an outer tube, defining an annular space there-between, the inner tube
delimiting an
inner passage for the circulation of the probes; and
- a pneumatic transport system, configured for supplying a flow of pressurized
gas
through the inner tube in a first direction for pushing the probes into the
probe receiving
finger and in a second direction, opposite the first direction, for pushing
the probes out of
the probe receiving finger,
wherein
the device further comprises a head, to which the probe receiving fingers are
attached,
the head comprising a body defining, for each of the probe receiving fingers,
a gas conduit
for receiving a flow of pressurized gas from the pneumatic transport system,
each gas
conduit having a first end opening into the annular space between the inner
tube and the
outer tube of the respective probe receiving finger and a second end connected
to a gas
supply port for connection to a supply of pressurized gas, the gas conduits of
the different
probe receiving fingers being separated from each other fluidically.
The device according to the invention is advantageous. Indeed, since the probe
receiving fingers are isolated from each other from a fluidic point of view,
and further each
have their own inlet for pressurized gas, it is possible to insert and remove
probes from
these different fingers independently, which allows producing different types
of isotopes,
with different activation times, or to produce the same isotopes sequentially
in time in the
different probe receiving fingers, such that there are always activated
isotopes available.
15 The device therefore results in an improved flexibility with respect to
the manufacturing of
activated isotopes.
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In addition, the design of the device is particularly compact and robust. It
is therefore
particularly adapted for being used in the core of a heavy water reactor, in
particular a
CANDU reactor, as described above, where the space available is relatively
small. In
particular, since the device may for example include six probe receiving
fingers, a relatively
high number of probes may be irradiated simultaneously, thus resulting in an
improved
productivity.
Furthermore, the device according to the invention allows the insertion of
much larger
probes than was possible with prior art installations, and in particular of
cylindrical probes
having a diameter up to 12 mm. Therefore, this device results in an improved
productivity,
since a greater amount of isotopes may be produced in the device within a
given time.
The fact that both spherical and cylindrical probes may be used also increases
the
flexibility of use of the device.
The compact and stiff design of the device is also advantageous compared to
prior art
devices, as it results in an increased resistance to earthquakes.
The device may further comprise one or more of the following features, taken
alone,
or according to any technically possible combination:
- The outer tube is attached to the head through clamping.
- The body comprises an upper part and a lower part, attached to each
other, in
particular by means of screws, and the outer tube comprises a radial annular
flange which
is clamped between the upper part and the lower part.
- The device further comprises first seals for pressure-tight sealing of
the inner
passage of each inner tube and/or second seals for pressure-tight sealing of
the annular
space between the inner tube and the outer tube.
- The gas supply port is inserted into the gas conduit in a pressure-tight
manner.
- The gas conduit comprises a first conduit portion extending perpendicular to
the
longitudinal axis of the respective probe receiving finger from the first end
of the conduit.
- The gas conduit further comprises a second conduit portion extending
perpendicular to the first conduit portion, the second conduit portion
comprising a first end
opening into the first conduit portion and a second end forming the second end
of the
conduit, the second end of the conduit being located at a top surface of the
head.
- The body comprises an upper part and a lower part, attached to each
other, in
particular by means of screws, the gas conduits being formed in the upper
part.
- The device further comprises, for each probe receiving finger, a
connection port
for connection of the probe receiving finger to a probe handling system for
transporting the
probes into and/or out of the probe receiving finger, the connection port
forming a pressure-
tight connection with the probe receiving finger.
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- The device further comprises a lifting handle, attached to the body of
the head, for
lifting the device in one piece.
- The pneumatic transport system comprises a dedicated gas supply line for
each
gas conduit, each gas supply line being connected to the gas supply port of
the
corresponding gas conduit.
According to another aspect, the invention relates to a diverter for
selectively
connecting one of a plurality of inlet tubes, each inlet tube being intended
to be connected
to a respective probe receiving finger intended for receiving probes for their
irradiation in
the core of a nuclear reactor to one single outlet tube intended to be
connected to a probe
handling system, said diverter comprising:
- n inlet ports, n being an integer greater than or equal to three, each
inlet port
comprising an inlet tube fitting, the inlet tube fitting comprising an inlet
end connected to a
corresponding inlet tube;
- one single outlet port comprising an outlet tube fitting, the outlet tube
fitting
comprising an outlet end connected to the outlet tube,
- a connection tube comprising an inlet end, connected to an outlet end of
one of the
inlet tube fittings and an outlet end, connected to an inlet end of the outlet
tube fitting, the
inlet port to which the connection tube is connected being an active inlet
port and the
remaining inlet ports being inactive inlet ports;
wherein
the inlet end of the inlet tube fitting is configured to form a pressure-tight
connection
with the inlet tube and the outlet end of the inlet tube fitting is configured
to form a pressure-
tight connection with the inlet end of the connection tube ; and
the inlet tube fittings are arranged on at least a portion of a circle, the
outlet tube
fitting being arranged in the alignment of the center of the circle, taken
along a longitudinal
direction of the diverter extending perpendicular to the plane of the circle.
The diverter according to the invention is particularly advantageous. Indeed,
it allows
increasing the irradiation capacities, due to the fact that several probe
receiving fingers, and
for example six probe receiving fingers, located in the core of the nuclear
reactor may be
used without having to increase the number of system components for handling
the probes
located outside of the core of the nuclear reactor. In addition, thanks to the
pressure-
tightness of the connections, in particular on the inlet side, the diverter is
integrated into the
containment boundary, which makes it possible to avoid the use of containment
penetration
valves. Indeed, normally, containment penetration valves are located at the
containment
boundary to prevent primary fluid from exiting the containment in case of a
leakage. With
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the diverter according to the invention, since the connections of the diverter
are pressure-
tight, there is no risk of primary fluid exiting the containment at the
diverter.
The diverter may further comprise one or more of the following features, taken
alone,
or according to any technically possible combination:
5 -
The diverter further comprises a plurality of closure plugs inserted into the
outlet
ends of the inlet tube fittings of the inactive inlet ports so as to close
these inlet tube fittings
in a pressure-tight manner.
This feature contributes to making the diverter part of the containment
enclosure.
Indeed, since all inactive inlet ports are closed in a pressure-tight manner,
there is no risk
of primary fluid exiting the containment through these inactive inlet ports in
case of a
leakage.
- The inlet end of the outlet tube fitting is configured to form a pressure-
tight connection
with the outlet end of the connection tube and the outlet end of the outlet
tube fitting is
configured to form a pressure-tight connection with the outlet tube.
- The connection tube is displaceable between n positions, each position
corresponding to the connection of the inlet end of the connection tube to the
outlet end of
one of the n inlet tube fittings and of the outlet end of the connection tube
to the inlet end of
the outlet tube fitting, wherein, in each position, the inlet port to which
the connection tube
is connected is an active inlet port and the remaining inlet ports are
inactive inlet ports.
- The connection tube is configured to be manually displaceable between the n
positions.
- The outlet tube fitting is supported by an outlet support structure, said
outlet support
structure being displaceable in translation along the longitudinal direction
of the diverter.
- The diverter further comprises a detector configured to detect which one
of the inlet
ports is the active inlet port.
- The detector comprises an inlet plug and socket system comprising:
- an inlet socket for each inlet port, the inlet socket being arranged at
the inlet
tube fitting of the inlet port, and
- an inlet plug, attached to the inlet end of the connection tube,
the detector being configured in such a manner that, when the inlet plug is
plugged
into the inlet socket of one of the inlet ports, a signal indicative of the
fact that the
corresponding inlet port is the active inlet port is generated.
- The plug and socket system is configured in such a manner that the inlet
plug can
only be plugged into the inlet socket of the inlet port to which the inlet end
of the connection
tube is connected.
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- The inlet plug is attached to the connection tube through a flexible
connection link,
for example a chain or a cord, the length of the flexible connection link
being chosen in such
a manner that the inlet plug can only be plugged into the inlet socket of the
inlet port to
which the inlet end of the connection tube is connected.
- The plugging of the inlet plug into the inlet socket is configured to close
an electric
circuit, the closing of the electric circuit resulting in the generation of
the signal indicative of
the fact that the inlet port at which the inlet socket is located is the
active inlet port.
- The detector is further configured for detecting a breakage in a wire of
an electric
cable arriving at the inlet socket.
- The diverter further comprises an outlet plug and socket system comprising:
- an outlet socket arranged at the outlet tube fitting of the outlet port,
and
- an outlet plug, attached to the outlet end of the connection tube,
the outlet plug being intended to be plugged into the outlet socket.
- The outlet tube is connected to one or both of a decay station for
receiving the
probes after their irradiation in the core of the nuclear reactor, in
particular in the probe
receiving fingers, and a probe supply unit.
- The nuclear reactor is a heavy water reactor, in particular a CANDU
reactor.
The invention also relates to an installation for producing activated probes
in the
core of a heavy water nuclear reactor, in particular a CANDU reactor,
comprising:
- a device for subjecting probes to irradiation in the core of a nuclear
reactor as
described above, extending into the core of the nuclear reactor and intended
for receiving
probes in view of their irradiation in the core of the nuclear reactor;
- a probe supply system, configured for supplying non-activated probes to
the device
for subjecting probes to irradiation in the core of a nuclear reactor,
- a decay station configured for receiving the probes irradiated in the core
of the
nuclear reactor from the device for subjecting probes to irradiation in the
core of a nuclear
reactor,
- a probe discharge system for discharging the probes from the
installation, an inlet
of the probe discharge system being connected to the decay station; and
- a probe drive system, configured for transporting the probes through the
installation, the probe drive system being preferably a pneumatic system.
The invention also relates to an installation for producing activated probes
in the
core of a heavy water nuclear reactor, in particular a CANDU reactor,
comprising:
- a device for subjecting probes to irradiation in the core of the nuclear
reactor,
extending into the core of the nuclear reactor and intended for receiving
probes in view of
their irradiation in the core of the nuclear reactor;
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- a probe supply system, configured for supplying non-activated probes to
the device
for subjecting probes to irradiation in the core of the nuclear reactor;
- a decay station configured for receiving the probes irradiated in the
core of the
nuclear reactor from the device for subjecting probes to irradiation in the
core of a nuclear
reactor,
- a probe discharge system for discharging the probes from the
installation, an inlet
of the probe discharge system being connected to the decay station;
- a diverter as described above, each inlet port of the diverter being
connected to a
probe receiving finger of the device for subjecting probes to irradiation in
the core of the
nuclear reactor and the outlet port of the diverter being connected to one or
both of the
decay station and the probe supply system; and
- a probe drive system, configured for transporting the probes through the
installation, the probe drive system being preferably a pneumatic system.
According to a particular embodiments of the installation, the device for
subjecting
probes to irradiation in the core of the nuclear reactor is a device as
described above.
The invention also relates to a heavy water reactor, comprising:
- a calandria housing a plurality of calandria tubes, each calandria tube
containing a
fuel element, a heavy water moderator flowing through the calandria;
- a reactivity mechanism deck, located above the calandria, and comprising
at least
one port, for example a view port, and
- an installation as described above.
According to particular embodiments of the heavy water reactor:
- The device for subjecting probes to irradiation in the core of the
nuclear reactor is a
device as described above, and the probe receiving fingers of the device for
subjecting
probes to irradiation in the core of the nuclear reactor extend vertically
downwards into the
calandria through the port of the reactivity mechanism deck.
- The heavy water reactor further comprises a guide tube, inserted into the
port of the
reactivity mechanism deck, the probe receiving fingers of the device being
inserted into the
guide tube and the head of the device bearing on a top surface of the guide
tube.
- The heavy water reactor is a CANDU type reactor.
The invention will be better understood upon reading the following
description, given
only by way of example with reference to the appended drawings, in which:
- Figure 1 shows a typical CANDU reactor assembly;
- Figure 2 shows a partial cross-sectional side view of the heavy water
reactor
calandria shown in Figure 1;
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- Figure 3 shows a top view of the heavy water reactor shown in Figure 1,
showing
view port locations, schematically illustrating the locations of reactivity
control units in a
reactivity mechanism deck positioned above the calandria;
- Figure 4 shows an end view of the heavy water reactor shown in Fig. 1;
- Figure 5 shows a reactivity mechanism deck of the heavy water reactor shown
in
Fig. 1, showing the view port location;
- Figure 6 shows a side view of the heavy water reactor shown in Fig. 1,
showing the
view port location with a device for subjecting probes to irradiation in the
core of a nuclear
reactor in accordance with an embodiment of the present invention in place;
- Figure 7 is a cross-sectional schematic view of the device according to the
invention;
- Figure 8 is an enlarged view of the top part of Figure 7;
- Figure 9 is a schematic side view of a diverter according to another
aspect of the
invention;
- Figure 10 is a schematic side view of a diverter according to another
aspect of the
invention;
- Figure 11 is a schematic view of a detail of the diverter of figure 9;
and
- Figure 12 is a schematic view of an installation for producing activated
probes in the
core of a nuclear reactor.
In the following description, the invention is described in the context of a
CANDU
heavy water reactor. However, the invention may also be used in any other type
of heavy
water reactor.
Fig. 1 shows a typical CANDU reactor assembly. The typical CANDU reactor
assembly has separate pressure boundaries categorized as:
- the primary cooling loop where the fuel is contained,
- the moderator system, the function of the moderator being to slow the
neutrons; and
- the end shield which provides radiation shielding and supports the
primary cooling
loop fuel channels.
The moderator system is a separate system, isolated from the primary cooling
loop.
In the example shown in Figure 1, the primary cooling loop components comprise
fuel
channel end fittings 10 and feeder pipes 11. The moderator system components
comprise
the calandria 1, calandria shell 2, calandria tubes 3, inlet-outlet strainer
8, moderator outlet
12, moderator inlet pipe 13, pipe to moderator expansion head tank 18,
moderator
discharge pipes 20, rupture disc 21, calandria nozzles for reactivity control
units 22 and
calandria tubesheet 29. The end shield includes the endshield embedment ring
4, fuelling
15
tubesheet 5, endshield lattice tube 6, endshield cooling pipes 7, and steel
ball shielding 9.
The ports that penetrate the moderator system include ports for horizontal
flux detectors
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units and liquid injection units 14, ion chambers 15, view port 23, shutoff
unit 24, adjustor
unit 25, control absorber unit 26, liquid zone control unit 27 and vertical
flux detector unit
28. The assembly is housed in a concrete reactor vault wall 17, with curtain
shielding slabs
19, and the overall assembly is protected against seismic events with
earthquake restraints
16.
The reactor core enclosure shown in Fig. 1 is in the form of a calandria 1,
which is
delimited by a horizontal cylindrical shell 2. A plurality of calandria tubes
3 are housed inside
of calandria shell 2. The heavy water moderator flows into and out of the
volume inside
calandria 1 via piping 12,13 delimited between the inner surface of calandria
shell 2, the
outer surfaces of calandria tubes 3 and calandria tubesheet 29. The primary
coolant loop,
which contains the fuel elements, is physically separate and flows from the
feeder pipes 1 1 ,
through the fuel channel end fitting 10, and down the pressure tube (a.k.a.
fuel channel
containing the fuel element) and out the opposite fuel channel end fitting 10
and into the
opposite feeder pipe 11. As schematically shown in the partial cross-
sectional view of Fig.
2, heavy water moderator is contained inside the volume delimited between the
inner
surface of calandria shell 2, the outer surfaces of calandria tubes 3 and
calandria tubesheet
29. Each calandria tube 3 surrounds a pressure tube (a.k.a. fuel channel) 44
housing a
plurality of fuel elements 51 therein. Calandria tubes 3, along with a gas
filled annular space
48 maintained by garter spring spacers 46, provide a buffer between pressure
tubes 44 and
the moderator heavy water so heated heavy water primary coolant in pressure
tubes 44
does not boil the heavy water moderator. Primary coolant flows into pressure
tubes 44 from
a cold leg of a primary coolant loop from a feeder pipe 11 into an end fitting
10 and flows to
receive heat from fuel elements 51, then flows out of pressures tubes 44 at
the opposite
end fitting 10 and out a feeder pipe 11 to a hot leg of the primary coolant
loop for flowing
through a steam generator located downstream in the hot leg. Closure plugs 52
are on each
end fitting 10 to allow for on-line fueling.
Figure 1 further shows moderator inlet pipes 13 for providing cooled water
from a
moderator main circuit, moderator outlet pipes 12 for providing heated
moderator water
back to moderator main circuit for cooling and pressure discharge pipes 20 for
relieving
pressure inside calandria shell 2. A plurality of horizontally extending
neutron flux detector
units 14 extend horizontally through calandria 1 to monitor the neutron flux
in calandria 1
during the operation of reactor. Extending vertically through core are a
plurality of reactivity
control units therein.
Figure 3 shows a top plan view schematically illustrating the locations of
reactivity
control units in a reactivity mechanism deck 45 positioned above the calandria
1. Reactivity
mechanism deck holds all the reactivity control units that extend below
reactivity mechanism
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deck and penetrate calandria 1 from above. From Figure 1, the reactivity
control units
include vertically extending neutron flux detector units 28, liquid zone
control units 27,
adjuster units 25, control absorber units 26 and reactor shutoff units 24,
which are all need
to be available and capable of operating during the operation. In addition to
the reactivity
5 control units, reactivity mechanism deck 45 also includes two view ports
23 extending there-
through. A first view port 49, i.e., a high flux inspection port, is aligned
with a high flux region
of the reactor core and a second view port 50, i.e., a low flux inspection
port, is aligned with
a low flux region of the reactor core. View ports 49, 50 are used during the
periodic
inspection to monitor corrosion and wear of the reactor at two regions exposed
to different
10 levels of neutron flux.
Figure 4 shows a cross-sectional side view, which illustrates the positioning
of
reactivity mechanism deck 45 above calandria 1 with the view port 23 location.
An existing
thimble 53 is in place in the view port to allow insertion of a guide tube to
monitor neutron
flux during the initial startup of reactor when brand new fuel is provided
into the reactor. An
aluminum guide tube is typically provided with barium fluoride detectors
having a very high
sensitivity to neutron flux. Once the reactor is started up and neutron flux
is detected by the
barium fluoride detector, the aluminum guide tube is removed. Leaving the
aluminum guide
tube during normal operation would lead to permanent damage. After initial
startup, view
ports are available to have radioisotope production guide tubes inserted.
Figure 5 shows the reactivity mechanism deck 45 with the view port 23 location
as
well as relative location with respect to, shut off unit 24, adjustor unit 25,
control absorber
unit 26, liquid zone control unit 27 and vertical flux detector units 28.
The device 55 for subjecting probes to irradiation in the core of the nuclear
reactor
according to the invention is intended to be inserted into a port of the
reactivity mechanism
deck 45 of the nuclear reactor, more particularly into a spare port of the
reactivity
mechanism deck 45. The device 55 is advantageously intended to be inserted
into the view
port 23 of the reactivity mechanism deck 45.
As shown in Figure 6, the device 55 is preferably inserted into a guide tube
56, which
is itself inserted into the port of the reactivity mechanism deck 45, in
particular the view port
23. The guide tube 56 extends into the calandria 1 of the heavy water reactor,
and therefore
into the heavy water moderator. The guide tube 56 is preferably filled with
helium. In this
embodiment, the device 55 is therefore not directly in contact with the heavy
water
moderator contained in the calandria 1.
According to an alternative, the device 55 is inserted into the port of the
reactivity
15 mechanism deck, in particular the view port 23, and is in direct contact
with the heavy water
moderator contained in the calandria 1. This embodiment has, however, a lower
stability
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than the embodiment in which the device 55 is inserted into a guide tube 56
described
above.
The device 55 will now be described in detail with reference to Figures 6, 7
and 8.
The device 55 comprises:
- a plurality of probe receiving fingers 60;
- a head 62, to which the probe receiving fingers 60 are attached; and
- a pneumatic transport system 64, configured for transporting the probes
into and out
of the probe receiving fingers 60.
Each probe receiving finger 60 is configured for receiving a plurality of
probes in view
of their irradiation in the core of the nuclear reactor.
The probes for example have a cylindrical or a spherical shape. In the case of
a
spherical probe, the diameter of the probe is preferably lower than or equal
to 12 mm. In
the case of a cylindrical probe, the diameter of the probe is lower than or
equal to 12 mm,
and the height of the probe is lower than or equal to 100 mm.
The probe is preferably an irradiation target.
The irradiation target comprises an envelope encapsulating a core made of non-
fissile
material and comprising a suitable precursor material for generating
radionuclides, which
are to be used for medical and/or other purposes. More preferably, the
precursor material
converts to a desired radionuclide upon activating by exposure to neutron flux
present in
the reactor core. Useful precursor materials are Mo-98 and Yb-176, which are
converted to
Mo-99 and Lu-177, respectively. It is understood, however, that the invention
is not limited
to the use of a specific precursor material.
The envelope encapsulates the core in a hermetic manner. It is for example
made of
a metallic material. The core in particular comprises the precursor material
in powder form.
According to an alternative, the probe is a neutron flux measurement probe,
which is
used for measuring the neutron flux in the core.
Each probe receiving finger 60 defines a longitudinal axis L. When the device
55 is
inserted into the corresponding port of the reactivity mechanism deck 45, each
probe
receiving finger 60 extends vertically downwards into the core of the nuclear
reactor, and
more particularly into the calandria 1 of the nuclear reactor, the
longitudinal axis L thus
extending vertically downwards.
In the following description, the terms lower, upper, bottom and top are used
with
respect to the normal orientation of the device 55 in the use configuration,
i.e. when inserted
into the corresponding port of the reactivity mechanism deck 45.
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The number of probe receiving fingers 60 is preferably greater than or equal
to two,
for example greater than or equal to three, and more particularly equal to
six. The probe
receiving fingers 60 are for example arranged on the head 62 in a circle.
Each probe receiving finger 60 has a double walled structure comprising an
inner tube
68 and an outer tube 70, defining an annular space 72 there-between. The
annular space
72 is intended for receiving a circulation of pressurized gas from a
pressurized gas supply
system of the pneumatic transport system 64.
The inner tube 68 and the outer tube 70 extend coaxially and are centered on
the
longitudinal axis L of the probe receiving finger 60. The inner tube 68
delimits an inner
passage 69 for the circulation of the probes. The inner tube 68 is intended
for receiving the
probes in view of their irradiation in the core of the nuclear reactor.
The inner tube 68 and the outer tube 70 are preferably made of a metallic
material,
and for example of zirconium or stainless steel.
As shown in Figure 7, the outer tube 70 is closed at its bottom end 76. The
bottom
end 76 for example has a conical shape. However, other shapes may also be used
for the
bottom end 76.
The inner tube 68 has a bottom end 78 which extends at a distance, taken along
the
longitudinal direction L, of the bottom end 76 of the outer tube 70, and more
particularly at
a distance above the bottom end 76, such that the annular space 72
communicates, at a
bottom end 79 of the probe receiving finger 60, with the inner passage 69 of
the inner tube
68. Therefore, pressurized gas flowing downwards through the annular space 72
is able to
enter the inner tube 68 at the bottom end 78 thereof, and then to flow upwards
through the
inner passage 69 of the inner tube 68, pushing probes contained in the inner
tube 68
upwards and out of the probe receiving finger 60.
The device 55 further comprises, for each probe receiving finger 60, a
connection port
80 for connection of the probe receiving finger 60 to a tube of a probe
handling system for
transporting the probes into and/or out of the probe receiving finger 60.
The connection port 80 is located at an upper end 82 of the probe receiving
finger 60.
More particularly, the probe receiving finger 60 is intended to be connected,
through
the connector 80, to a decay station of a probe handling system and/or to a
probe supply
system configured for supplying non-activated probes to the device 55 for
subjecting probes
to irradiation in the core of a nuclear reactor.
The connection port 80 forms a pressure-tight connection with the probe
receiving
finger 60. More particularly, the connection port 80 is screwed into the upper
end 82 of the
15 probe receiving finger 60 in a pressure-tight manner. The connection
port 80 is further
configured for connection to a tube of a probe handling system in a pressure-
tight manner,
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for example by screwing to a corresponding connector of the tube of the probe
handling
system.
In the context of this invention, "pressure-tight" is in particular used with
reference to
the pressure prevailing in the guide tube 56 in case the guide tube 56 is
damaged. This
pressure is in particular defined based on the same design criteria as for the
containment
penetration valves. In other words, a "pressure-tight" connection or part is
in particular
capable of withstanding the pressure existing in the guide tube 56 in case the
guide tube
56 is damaged, in order to avoid leakage through these connections or parts.
In the example shown in Figures 7 and 8, the inner tube 68 extends through a
through-
hole delimited in the head 62. The upper end 86 of the inner tube 68 is
located above the
head 62.
The inner tube 68 is connected to the head 62, preferably by screwing. In
particular,
the inner tube 68 comprises a cylindrical lateral wall 87 outwardly delimiting
the inner
passage 69 of the inner tube 68 and a radial annular flange 88 which extends
outwardly
from the lateral wall 87 and bears on an upper surface 110 of the head 62. As
shown in
Figure 8, this radial annular flange 88 is screwed to the head 62 by means of
one or more
screws 89.
Preferably, the probe receiving finger 60 further comprises a sleeve 90
extending
between the upper end 86 of the inner tube 68 and the connection port 80. The
sleeve 90
has a tubular shape. It extends coaxially to the inner tube 68, and delimits
an inner passage
91 for the passage of the probes.
An upper section 94 of the sleeve 90 comprises a seat 96 for the connection
port 80.
More particularly, the upper section 94 of the sleeve 90 forms the upper end
82 of the probe
receiving finger 60. The connection port 80 is in particular screwed into the
seat 96 in a
pressure-tight manner.
A lower end 92 of the sleeve 90 is connected to the upper end 86 of the inner
tube 68,
and more particularly fitted over the upper end 86 of the inner tube 68. In
the example shown
in the figures, the sleeve 90 has an interior wall comprising a shoulder 93,
which bears on
an upper annular surface 97 of the inner tube 68. The portion of the sleeve 90
located below
this shoulder 93 extends over the inner tube 68. The portion of the sleeve 90
located below
the shoulder 93 has an inner diameter which is greater than the inner diameter
of the portion
of the sleeve 90 located above the shoulder 93 by the wall thickness of the
inner tube 68.
More particularly, the sleeve 90 comprises a central cylindrical section 100,
a radial
annular flange 102 at the lower end of the cylindrical section 100 forming the
lower end of
the sleeve 90 and the upper section 94 comprising the seat 96 at the upper end
of the
cylindrical section 100 and forming an upper end of the sleeve 90.
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The radial annular flange 102 bears on the upper surface 110 of the head 62.
In the
example shown in Figures 7 and 8, the radial annular flange 102 bears on the
upper surface
110 indirectly through the radial annular flange 88 of the inner tube 68. The
diameters of
the radial annular flange 102 and of the radial annular flange 88 are in
particular
substantially equal.
The sleeve 90 is connected to the head 62, in particular through screwing.
In the example shown in Figures 7 and 8, the radial annular flange 102 bears
on the
upper surface 110 indirectly through the radial annular flange 88 of the inner
tube 68 and
screws 89 are inserted through corresponding through holes formed in the
superimposed
radial annular flanges 88 and 102 and then screwed into a threaded hole formed
in the head
62, thus attaching both the inner tube 68 and the sleeve 90 to the head 62.
The radial annular flange 102 has an outer diameter which is greater than that
of the
central cylindrical section 100. It therefore extends outwards compared to the
central
cylindrical section 100.
In the example shown in the Figures, a recess 112 is formed in the upper
surface 110
of the head 62, the recess 112 receiving the radial annular flanges 88 and
102. The diameter
of the recess 112 is for example substantially equal to the diameter of the
radial annular
flanges 88 and 102.
The seat section 104 has an outer diameter which is greater than that of the
central
cylindrical section 100. In the example shown in the Figures, the outer
diameter of the seat
section 104 is the same as the outer diameter of the radial annular flange
102.
The probe receiving finger 60 delimits a cylindrical interior passage for the
passage of
the probes. This cylindrical interior passage extends downwards from the upper
end 82 of
the probe receiving finger 60. In the example shown in Figures 7 and 8, the
cylindrical
interior passage is successively delimited, from the top to the bottom of the
probe receiving
finger 60, by the sleeve 90 and the inner tube 68 of the probe receiving
finger 60. The inner
passage 91 of the sleeve 90 has substantially the same diameter as the inner
passage 69
of the inner tube 68. Therefore, the inner wall of the cylindrical interior
passage of the probe
receiving finger 60 has a smooth surface at the junction between the sleeve 90
and the
inner tube 68, thus facilitating the passage of the probes through the
cylindrical interior
passage.
At the bottom end of the cylindrical interior passage, the probe receiving
finger 60
includes a probe stop, which is configured for stopping the probes from moving
further
downwards. The probe stop is in particular formed in the bottom end 76 of the
outer tube
15 70.
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In the example shown in the Figures, the head 62 comprises a body 80
comprising an
upper part 81 and a lower part 83, connected to each other. The upper and
lower parts 81,
83 are preferably connected by screws (not shown). However, they may also be
connected
through other adapted connection means. The body 80 for example has a
substantially
5 cylindrical outer contour.
The outer tube 70 is clamped to the head 62 at its top end 74. More
particularly, the
outer tube 70 comprises a cylindrical lateral wall 75 outwardly delimiting the
annular space
72 between the inner tube 68 and the outer tube 70 and a radial annular flange
77, located
at the top end 74 of the outer tube 70, the radial annular flange 77 extending
radially
10 outwards from the cylindrical lateral wall 75. As shown in Figure 8, the
radial annular flange
77 is clamped between the upper and lower parts 81, 83 of the body 80 of the
head 62.
The fact that the outer tube 70 is clamped to the body 80 of the head 62
rather than
being screwed thereto individually is advantageous, since it makes it possible
to arrange
the probe receiving fingers 60 closer to each other, and therefore improves
the
15 compactness of the device 55.
The body 80 defines, for each probe receiving finger 60, a gas conduit 113 for
receiving a flow of pressurized gas from the pneumatic transport system 64. In
addition, the
device 55 comprises a gas supply port 119 for connection to a pressurized gas
supply line
120 of the pneumatic transport system 64 for supply of pressurized gas.
More particularly, the gas conduit 113 is formed by a bore formed in the body
80. In
the example shown in Figures 7 and 8, the gas conduits 113 are formed in the
upper part
81 of the head 62. Each gas conduit 113 has a first end 115 opening into the
annular space
72 between the inner tube 68 and the outer tube 70 of the respective probe
receiving finger
60 and a second end 117 connected to the gas supply port 119.
The gas conduits 113 of the different probe receiving fingers 60 are separated
from
each other fluidically.
The gas supply port 119 is connected to the conduit gas 113 in a pressure-
tight
manner. More particularly, it is screwed to the body 80 in a pressure-tight
manner. Each
gas supply port 119 is connected to its own pressurized gas supply line 120.
The conduit 113, the annular space 72, the inner tube 68 and the outer tube 70
are
configured in such a manner that pressurized gas supplied at the gas supply
port 119 of a
considered probe receiving finger 60 flows through the conduit 113 into the
annular space
72, and then flows down the annular space 72 until reaching the bottom of the
probe
receiving finger 60, and then flows upwards through the inner passage 69 of
the inner tube
68 so as to push the probes upwards out of the inner tube 68.
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In the example shown in Figures 7 and 8, each gas conduit 113 comprises a
first
conduit portion 121 extending perpendicular to the longitudinal axis L of the
respective
probe receiving finger 60 from the first end 115 of the conduit 113 and a
second conduit
portion 123 extending upwards and perpendicular to the first conduit portion
121. The
second conduit portion 123 comprises a first end opening into the first
conduit portion 121
and a second end forming the second end 117 of the conduit 113, and connected
to the
gas supply port 119. In this example, the first conduit portion 121 comprises,
at the junction
with the second conduit portion 123, a cylindrical conduit section and, at its
first end, an
annular chamber 127 extending around the inner tube 68, above the annular
space 72 and
communicating fluidically with the annular space 72. In the example shown on
the Figures,
the first conduit portion 115 opens out through a lateral opening 129 into a
lateral surface
130 of the body 80 due to manufacturing constraints. This lateral opening 129
is closed in
a pressure-tight manner using an adapted plug 131, which is, for example,
screwed into the
first conduit portion 115 in a pressure-tight manner.
According to an alternative (not shown in the drawings), the gas conduit 113
only
comprises the first conduit portion 115 and the gas supply port 119 is
connected to the
lateral opening 131 of the first conduit portion 115. This alternative can,
however, only be
used if there is sufficient space for a connection of a pressurized gas supply
line 120 on the
side of the body 80.
The device 55 further comprises first seals 140 for pressure-tight sealing of
the inner
passage 69 of each inner tube 68. The first seals 140 are in particular
inserted between the
radial annular flange 88 of each inner tube 68 and the radial annular flange
102 of the sleeve
90. They are in particular formed by annular rings inserted into a
corresponding recess of
the radial annular flange 88 or of the radial annular flange 102. The first
seals 140 prevent
fluid from outside the probe receiving finger 60, in particular the helium
contained in the
guide tube 56 or the moderator in the case where there is no guide tube, from
entering the
inner passage 69 of the inner tube 68.
The device 55 further comprises second seals 145 for pressure-tight sealing of
the
annular space 72 between the inner tube 68 and the outer tube 70. The second
seals 145
are in particular inserted between the radial annular flange 88 of each inner
tube 68 and the
upper part 81 of the body 80 and/or between the radial annular flange 77 of
each outer tube
70 and the upper part 83 of the body. They are in particular formed by annular
rings inserted
into corresponding recesses of the upper part 81 of the body 80, respectively
the lower body
portion or of the radial annular flange 88 or of the radial annular flange 77.
The second seals
145 ensure that the different probe receiving fingers 60 are independent of
each other, by
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preventing a fluidic communication between the fingers 60 through the space
between the
upper and the lower parts 81, 83 of the body 80.
In the embodiment shown in the Figures, the device 55 also comprises third
seals 148
for preventing the helium present in the guide tube 56 from escaping from the
guide tube
56 through the device 55. These third seals 148 are located between the bottom
of the
radial annular flange 77 of the outer tube 80 and the lower part 83 of the
body 80.
The device 55 is constructed in a pressure-tight manner.
The device 55 is further constructed in such a manner that the flow of gas
through
each probe receiving finger 60 can be controlled independently.
The pneumatic transport system 64 is configured for supplying a flow of
pressurized
gas through the inner tube 68 in a first direction for pushing the probes into
the probe
receiving finger 60 and in a second direction, opposite the first direction,
for pushing the
probes out of the probe receiving finger 60.
More particularly, for introducing the probes into the probe receiving finger
60, the
pneumatic transport system 64 is configured for activating a flow of gas which
enters the
probe receiving finger 60 at the connection port 80 and flows downwards
through the inner
tube 68, thus pushing the probes into the probe receiving finger 60. The
device 55 is further
configured such that the pressurized gas introduced into the inner passage 69
of the inner
tube 68 then flows from the bottom end 78 of the inner tube 68 into the
annular space 72,
and then flows upwards through the annular space 72 and through the gas
conduit 82 and
is then evacuated through the gas supply port 119.
For discharging the probes from the probe receiving finger 60 after their
irradiation in
the core of the nuclear reactor, the pneumatic transport system 64 is
configured for
activating, for each probe receiving finger 60, a flow of gas through the
pressurized gas
supply line 120 of the considered probe receiving finger 60, through the gas
supply port
119, through the gas conduit 113 and into the annular space 72, then down to
the bottom
of the annular space 72 and up the inner passage 69 of the inner tube 68 so as
to push the
probes contained in the probe receiving finger 60 upwards. The pressurized gas
is then
evacuated through the connector 80 located at the upper end 82 of the probe
receiving
finger 60 together with the probes.
As described previously, the pneumatic transport system 64 comprises one
pressurized gas supply line 120 for each gas supply port 119, each pressurized
gas supply
line 120 being connected to a corresponding gas supply port 119. The
pressurized gas
supply lines are connected to a common gas supply source. Each pressurized gas
supply
line 120 comprises a valve configured for selectively opening or closing the
pressurized gas
supply line 120 such that the supply of pressurized gas to each probe
receiving finger 60
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may be controlled independently by the pneumatic transport system 64.
Therefore, the
pneumatic transport system 64 is further configured for controlling
pressurized gas supply
to each probe receiving finger 60 independently. The probes contained in the
probe
receiving fingers 60 may therefore be discharged from each probe receiving
finger 60
independently of the other probe receiving fingers 60.
The device 55 further comprises a lifting handle 150 for lifting the device 55
as a whole,
for example for lifting the device 55 out of the port 23 of the reactivity
mechanism deck 45.
The lifting handle 150 is for example formed by an annulus attached to the
body 80, and
more particularly on the upper surface 110 of the upper part 81 of the body
80.
The device 55 according to the invention is advantageous. Indeed, since the
probe
receiving fingers 60 are isolated from each other from a fluidic point of
view, and since the
supply of pressurized gas to each probe receiving finger 60 may further be
controlled
independently for each probe receiving finger 60 through the corresponding
connector 80
or gas supply port 119, it is possible to insert and remove probes from the
different probe
receiving fingers 60 independently. This allows producing different types of
isotopes, with
different activation times, or producing the same isotopes sequentially in
time in the different
probe receiving fingers 60, such that there are always activated isotopes
available. The
device 55 therefore results in an improved flexibility with respect to the
manufacturing of
activated isotopes.
In addition, the design of the device 55 is particularly compact and robust.
It is
therefore particularly adapted for being used in the core of a heavy water
reactor, in
particular a CANDU reactor, as described above, where the space available is
relatively
small. In particular, since the device 55 may for example include six tubes, a
relatively high
number of probes may be irradiated simultaneously, thus resulting in an
improved
productivity.
Furthermore, the device 55 according to the invention allows the insertion of
much
larger probes than was possible with prior art installations, and in
particular of cylindrical
probes having a diameter up to 12 mm. Therefore, this device 55 results in an
improved
productivity, since a greater amount of isotopes may be produced in the device
within a
given time.
The fact that both spherical and cylindrical probes may be used also increases
the
flexibility of use of the device 55.
The compact and stiff design of the device 55 is also advantageous compared to
prior
art devices, as it results in an increased resistance to earthquakes.
According to another aspect, the invention also relates to a diverter 200 for
selectively
connecting one of a plurality of inlet tubes 208 to one single outlet tube
216.
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Each inlet tube 208 is intended to be connected to a respective probe
receiving finger
intended for receiving probes for their irradiation in the core of the nuclear
reactor.
The outlet tube 216 is intended to be connected to a probe handling system,
and for
example to one or both of a decay station for receiving the probes after their
irradiation in
the probe receiving fingers and a probe supply system for supplying non-
activated probes.
The decay station is intended for temporary storage of the probes which were
discharged from the probe receiving fingers after irradiation in the core of
the nuclear
reactor, so as to allow for a decay of the activity of these probes, prior to
their transfer to a
discharge system.
In the present patent application, the terms "inlet" and "outlet" are used
with respect
to a situation in which the probes circulate from the inlet tube 208 to the
outlet tube 216.
This situation corresponds to the discharge of activated probes from the core
of the nuclear
reactor. Of course, the diverter 200 may also be used in a situation in which
the probes
circulate from the outlet tube 216 to the inlet tube 208, for example when non-
activated
probes are transported from the probe supply system connected to the outlet
tube 216 into
the core of the nuclear reactor. The direction of displacement of the probes
through the
diverter is in particular determined by the direction of flow of the
pressurized gas.
The diverter 200 is located outside of the core of the nuclear reactor.
The diverter 200 will now be described in detail with reference to Figures 9
to 11.
The diverter 200 comprises n inlet ports 202, n being an integer greater than
or equal
to three. The number of inlet ports 202 is for example equal to 6.
This diverter 200 is in particular adapted for being connected, on its inlet
side, to the
device 55 for subjecting probes to irradiation in the core of the nuclear
reactor described
above with reference to Figures 6 to 8. In this case, the diverter 200 has as
many inlet ports
202 as there are probe receiving fingers 60 in the device 55 for subjecting
probes to
irradiation in the core of the nuclear reactor.
Each inlet port 202 comprises an inlet tube fitting 204. The inlet tube
fitting 204
comprises an inlet end 206 connected to an inlet tube 208. For example, for
each inlet port
202, the inlet tube 208 is a tube having an inlet end connected to one of the
probe receiving
fingers 60, and in particular to the connecting port 80 of one of the probe
receiving fingers
60.
As can be seen in Figure 10, the inlet ports 202 are arranged on at least a
portion of
a circle, the circle defining a circle plane P. In the example shown in Figure
10, the inlet
ports 202 are arranged on a circle, the circle defining the circle plane P.
However, the inlet
15
ports 202 may, according to an alternative, be arranged only on a portion of a
circle, the
circle defining the circle plane F'.
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According to one example, the angular spacing between adjacent inlet ports 202
is
regular. It is for example identical between any pair of adjacent inlet ports
202. For example,
in the example shown in Figure 10, in which the diverter 200 comprises exactly
six inlet
ports 202, the inlet ports 202 form a circle with an angular spacing equal to
about 360/6
5 degrees between adjacent inlet ports 202.
According to an alternative, the angular spacing between adjacent inlet ports
202 is
not regular or the angular spacing between adjacent inlet ports 202 is not
identical between
all pairs of adjacent inlet ports 202. For example, the angular spacing
between adjacent
inlets ports 202 is identical, except for the two inlet ports 202 located at
the ends of the
10 circle portion.
In the example shown in Figures 9 to 11, the inlet ports 202 are fixed to an
inlet support
structure 210. The inlet support structure 210 extends in the circle plane P.
The inlet support
structure 210 is fixed in position, which means that it is not movable. The
inlet support
structure 210 is for example plate-shaped.
15 The diverter 200 further comprises one single outlet port 211,
comprising an outlet
tube fitting 212. The outlet tube fitting 212 comprises an outlet end 214
configured to be
connected to an outlet tube 216.
The outlet tube fitting 212 is arranged in the alignment of the center C of
the circle,
taken along a longitudinal direction A of the diverter 200. The longitudinal
direction A is a
20 direction extending perpendicular to the plane P of the circle. The
outlet tube fitting 212 has
been drawn schematically in broken lines on Figure 10, the broken lines
indicating that the
outlet tube fitting 212 is located in a plane parallel to the plane of Figure
10, the plane of
Figure 10 being the plane P of the circle.
In the example shown in Figure 9, the outlet tube fitting 212 is fixed to an
outlet support
structure 218. The outlet support structure 218 is for example plate-shaped.
The outlet support structure 218 is displaceable in translation along the
longitudinal
direction A of the diverter 200. The direction of displacement is shown by
arrow "D" in Figure
9. Translation of the outlet support structure 218 along the longitudinal
direction A moves
the outlet support structure 218 and therefore also the outlet tube fitting
212, and changes
the distance between the outlet tube fitting 212 and the inlet tube fittings
204. Preferably,
the outlet support structure 218 is movable in translation along the
longitudinal direction A
between two positions, in which it may be fixed, a first end position
corresponding to the
use position of the diverter 200, shown in Figure 9, and a second end position
in which the
outlet support structure 218 is spaced further away from the inlet support
structure 210 than
in the first position.
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The diverter 200 further comprises a connection tube 220 comprising an inlet
end 222,
connected to an outlet end 224 of one of the n inlet tube fittings 204 and an
outlet end 226,
connected to an inlet end 228 of the outlet tube fitting 212, thus forming a
path for the
circulation of the probes from this inlet port 202 to the outlet port 212, and
therefore between
the inlet tube 208 connected to the inlet port 202 and the outlet tube 216
connected to the
outlet port 212.
In the example shown in Figure 9, the connection tube 220 has a curved shape
and
comprises two substantially straight end sections and a curved intermediate
section in-
between. The transition between the curved intermediate section and each of
the
substantially straight end sections is continuous, i.e. without angles. In the
example shown
in Figure 9, the intermediate section bends continuously between its two ends.
More
particularly, the intermediate section includes a concave section and a convex
section
separated by an inflexion point. In particular, the inflexion point is located
in the geometric
middle of the central axis of the intermediate section, measured along the
central axis of
the intermediate section. This continuous bending and the absence of angles
along its
length allows for a particular smooth displacement of the probes through the
connection
tube, despite the changes of direction.
The inlet end 206 of each inlet tube fitting 204 is configured for forming a
pressure-
tight connection with a respective inlet tube 208. The outlet end 224 of each
inlet tube fitting
204 is configured for forming a pressure-tight connection with the inlet end
222 of the
connection tube 220. For example, the inlet end 206 and the outlet end 224 of
the inlet tube
fitting 204 form pressure-tight screw connections respectively with the inlet
tube 208 and
with the inlet end 222 of the connection tube 220.
Optionally, the inlet end 228 of the outlet tube fitting 212 is configured for
forming a
pressure-tight connection with the outlet end 224 of the connection tube 220,
and the outlet
end 214 of the outlet tube fitting 212 is configured for forming a pressure-
tight connection
with the outlet tube 216. For example, the inlet end 228 and the outlet end
214 of the outlet
tube fitting 212 and the inlet end 206 and the outlet end 224 of the inlet
tube fitting 204
respectively form pressure-tight screw connections with the outlet end 224 of
the connection
tube 220 and with the outlet tube 216.
The inlet port 202 corresponding to the inlet tube fitting 204 to which the
connection
tube 220 is connected is an active inlet port and the remaining n-1 inlet
ports are inactive
inlet ports.
In this context, "active" means that this inlet port 202 is the one through
which the
probes travel into the connection tube 220, while no probes circulate through
the "inactive"
inlet ports 202. In the example shown in Figure 9, the active inlet port is
the top inlet port
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202, while the remaining five inlet ports 202 are inactive. As will be
explained later, the
active inlet port 202 may be varied by displacing the connection tube 220.
The diverter 200 further comprises a plurality of closure plugs 230,
schematically
represented in Figure 9.
When the connection tube 220 is connected to the active inlet port 202 and to
the
outlet port 211, closure plugs 230 are inserted into the outlet ends 224 of
the inlet tube
fittings 204 of the inactive inlet ports 202. The closure plugs 230 are
configured to close
these inlet tube fittings 204 in a pressure-tight manner. The closure plugs
230 are in
particular formed by screw caps, which are adapted for being screwed into the
outlet ends
224 in a pressure-tight manner.
When the connection tube 220 is not connected between an inlet port 202 and
the
outlet port 211, for example during activation of the probes in the core of
the nuclear reactor,
closure plugs 230 as described above are inserted into the outlet ends 224 of
all the inlet
tube fittings 204 and optionally into the inlet end 228 of the outlet tube
fitting 212.
The connection tube 220 is displaceable between n positions, each position
corresponding to the connection of the inlet end 222 of the connection tube
220 to the outlet
end 224 of one of the n inlet tube fittings 204 and of the outlet end 226 of
the connection
tube 220 to the inlet end 228 of the outlet tube fitting 212. In each position
of the connection
tube 220, the inlet port 202 to which the connection tube 220 is connected is
the active inlet
port and the remaining inlet ports 202 are inactive inlet ports. In the
example shown in
Figures 9 to 11, the connection tube 220 is therefore displaceable between six
different
positions. In each of the n positions of the connection tube 220, the diverter
creates a
pathway from one particular inlet tube 208 to the outlet tube 216.
In the case where each of the inlet tubes 208 is connected to a corresponding
probe
receiving finger 60 of the device 55 described above and the outlet tube 216
to a decay
station and/or to a probe supply system, depending on the position of the
connection tube
220, and in particular on the inlet port 202 forming the active inlet port,
the connection tube
220 allows for the circulation of the probes from the probe receiving finger
60 connected to
the active inlet port 202 of the diverter 200 into the decay station or from
the probe supply
system to the probe receiving finger 60 connected to the active inlet port
202.
The connection tube 202 is configured to be manually displaceable between the
n
positions through the following sequential steps:
- displacement of the outlet support structure 218 in the longitudinal
direction A of the
diverter 200, i.e. along arrow D, so as to increase the distance between the
inlet tube fitting
204 and the outlet tube fitting 212, i.e. to the right in Figure 9,
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- removal of the connection tube 202 from the inlet tube fitting 204 and
the outlet tube
fitting 212,
- positioning of the inlet end 222 and the outlet end 226 of the connection
tube 202 in
a position respectively facing the inlet tube fitting 204 of the inlet port
202 which is to be the
active inlet port 202 and the outlet tube fitting 212; and
- pressure-tight connection of the inlet and outlet ends 222, 226 of the
connection tube
220 to the inlet tube fitting 204 and the outlet tube fitting 212 in front of
which they are
positioned so as to establish a path between this inlet tube fitting 204 and
the outlet tube
fitting 212.
These steps are carried out by an operator.
The removal step in particular includes a sub-step of displacing the outlet
support
structure 218 in translation along the longitudinal direction A of the
diverter from its first
position into its second position.
The connection tube 220 cannot be rotated relative to the inlet support
structure 210
and the outlet support structure 218 without prior removal of the connection
tube 220 from
the inlet tube fitting 204 and the outlet tube fitting 212.
In the first position of the outlet support structure 218, the distance
between the inlet
support structure 210 and the outlet support structure 218 is such that the
connecting tube
220 is connected to one inlet tube fitting 204 on its inlet end 222 and to the
outlet tube fitting
212 on its outlet end 226, which means that the distance between the inlet
support structure
210 and the outlet support structure 218 is substantially equal to the
distance between the
inlet end 222 and the outlet end 226 of the connecting tube 220. In the second
position of
the outlet support structure 218, the distance between the inlet support
structure 210 and
the outlet support structure 218 is greater than in the first position, and
therefore allows
disconnecting the inlet end 222 and the outlet end 226 of the connection tube
220 from the
inlet tube fitting 204 and the outlet tube fitting 212.
The positioning step is in particular carried out by rotating the connection
tube 202
about an axis of rotation parallel to the longitudinal direction D and passing
through the
center C of the circle.
The connection step preferably includes a sub-step of displacing the outlet
support
structure 218 in translation along the longitudinal direction A of the
diverter from its second
position into its first position.
The diverter 200 further comprises a detector 240 configured to detect which
one of
the inlet ports 202 is the active inlet port. The detector 240 comprises an
inlet plug and
15 socket system 242, shown more particularly in Figure 11, and comprising:
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- an inlet socket 244 for each inlet port 202, the inlet socket 244 being
arranged at
the inlet tube fitting 204 of the inlet port 202, and
- an inlet plug 246, attached to the inlet end 222 of the connection tube
220.
The inlet plug and socket system 242 is configured in such a manner that the
plug
246 can only be plugged into the socket 244 associated with the inlet port 202
to which the
inlet end 222 of the connection tube 220 is connected. For example, the inlet
plug 246 is
attached to the connection tube 220 through a flexible connection link 250,
the length of the
flexible connection link 250 being chosen in such a manner that the plug 246
can only be
plugged into the socket 244 associated with the inlet port 202 to which the
inlet end 222 of
the connection tube 220 is connected. The flexible connection link 250 is for
example a
chain or a cord.
More particularly, each inlet socket 244 is fixed to the inlet support
structure 210
close to the corresponding inlet tube fitting 204, and for example at a
distance chosen
depending on the distance between adjacent or opposite inlet tube fittings
204.
In the example shown in Figure 10, the inlet socket 244 is for example aligned
with
the corresponding inlet tube fitting 204 along a radius of the circle. In this
example, the inlet
socket 244 is located closer to the center C of the circle than the
corresponding inlet tube
fitting 204. However, other geometries could also be used.
The detector 240 is configured in such a manner that, when the inlet plug 246
is
plugged into one of the inlet sockets 244, a signal indicative of the fact
that the
corresponding inlet port 202 is the active inlet port 202 is generated. In
particular, the
detector 240 is configured in such a manner that, for each pair of plug 246
and socket 244,
the plugging of the plug 246 into the socket 244 closes an electric circuit,
the closing of the
electric circuit resulting in the generation of the signal indicative of the
fact that the
corresponding inlet port 202 is the active inlet port. More particularly, the
pins of the plug
246 are short-circuited, such that the insertion of the plug 246 into the
socket 244 closes an
electrical circuit between the plug 246 and the socket 244 which is detected
by the detector
240 and triggers the emission of a corresponding signal.
In the embodiment shown in Figure 11, the electrical circuitry inside the
inlet socket
244 includes a two-wire cable 247 arriving at the inlet socket 244 and a
resistor 248
connected between the two wires of the cable 247. The two-wire cable 247 is
further
connected to a control unit of the nuclear reactor. In this embodiment, the
detector 240 is
configured for measuring the resistance between the two wires of the cable 247
to
determine whether a given inlet port 202 is active or not. If the inlet plug
246 is plugged into
a given inlet socket 244, the resistance measured between the two wires of the
cable 247
is substantially zero due to the short-circuit generated by the inlet plug
246. It the inlet plug
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246 is not plugged into the inlet socket 244, the resistance between the two
wires of the
cable 247 is equal to the resistance of the resistor 248.
The detector 240 is further configured for detecting a breakage of the two
wires of
the cable 247 arriving to the inlet sockets 244. Indeed, in case one of the
two wires of the
5 cable is broken, an infinite resistance is measured between the lines
247.
According to one embodiment, the diverter 200 may include an outlet plug and
socket system located at the outlet side of the diverter 200, and comprising:
- an outlet socket arranged at the outlet tube fitting 212 of the outlet
port 211, and
- an outlet plug, attached to the outlet end 226 of the connection tube
220,
10 the outlet plug being intended to be plugged into the outlet socket.
This plug and socket system is analogous to the plug and socket system 242
described above, and will therefore not be described in detail.
The diverter 200 according to the invention is advantageous. Indeed, it allows
connecting more than three, and in particular six, inlet tubes 208, for
example each
15 connected to a respective probe receiving finger 260, to a probe
handling system, and in
particular a decay station, in a compact and pressure-tight manner. More
particularly, the
diverter 200 allows increasing the irradiation capacities due to the fact that
several probe
receiving fingers, and for example six probe receiving fingers, located in the
core of the
nuclear reactor may be used without having to increase the number of system
components
20 for handling the probes located outside of the core of the nuclear
reactor. This is particularly
advantageous in the case of a heavy water reactor, such as the CANDU reactor.
Indeed,
when the probes are removed from the core, they are highly radioactive, and
need to spend
some time in a decay station, prior to being discharged from the nuclear
reactor through a
discharge system and to being transported to the client. Due to the fact that
only little space
25 is available in the CANDU reactor for the irradiation probe activation
system, in the case
where several fingers 60 are used for the activation of probes in the core, it
is not possible
to provide dedicated decay and discharge systems for each probe receiving
finger 60. The
above-described diverter 200 overcomes this issue by allowing to selectively
connect one
of the n probe receiving fingers 60 to one single decay station and discharge
system
depending on the needs. It therefore provides a compact solution for handling
the activated
probes.
Due to the pressure-tight implementation of the tube connections of the
diverter 200,
the diverter 200 also has the advantage of integrating the diverter 200 in the
containment,
which allows renouncing to certain containment penetration valves. Indeed,
normally,
15 containment penetration valves are located at the containment boundary
to prevent primary
fluid from exiting the containment in case of a leakage. In the present case,
since all the
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connections of the diverter 200 are pressure-tight, there is no risk of
primary fluid exiting the
containment at the diverter 200.
Providing pressure-tight closure caps 230 for the ends of the fittings 204,
212 which
are not being used also contributes to the pressure-tightness of the diverter
200, since there
is no risk of primary fluid exiting the containment through these fitting
ends.
Finally, additional safety is provided by the detector 240, which is able to
confirm which
inlet port 202 is active, and is further able to detect a breakage in the
lines 247 arriving at
the inlet sockets 244.
The invention also relates to an installation 290 for producing activated
probes in the
core of a heavy water nuclear reactor, in particular a CANDU reactor, as shown
schematically in Figure 12, comprising:
- a device for subjecting probes to irradiation in the core of a nuclear
reactor,
extending into the core of the nuclear reactor and intended for receiving
probes in view of
their irradiation in the core of the nuclear reactor;
- a probe supply system 300, configured for supplying non-activated probes to
the
device for subjecting probes to irradiation in the core of a nuclear reactor;
- a decay station 330 configured for receiving the probes irradiated in the
core of the
nuclear reactor from the device for subjecting probes to irradiation in the
core of a nuclear
reactor,
- a probe discharge system 350 for discharging the probes from the
installation 290,
the inlet of the probe discharge system 350 being connected to the decay
station 330; and
- a probe drive system 370, configured for transporting the probes through
the
installation 290.
The probe drive system 370 is preferably a pneumatic system.
The probe supply system 300, the probe discharge system 350 and the probe
drive
system 370 are known and are therefore not described in detail.
The installation 290 may further comprise a diverter 200 as described above,
each
inlet tube 208 being connected to a respective probe receiving finger 60 of
the device 55
for subjecting probes to irradiation in the core of a nuclear reactor and the
outlet tube 216
of the diverter 200 being connected to one or both of the decay station 330
and the probe
discharge system 350.
In particular, the outlet tube 216 may be connected to a connection part 217
including one inlet port connected to the outlet tube 216 and two outlet
ports, one outlet port
connected to the decay station 330 and one outlet port connected to the probe
supply
system 300. Therefore, the diverter 200 may be used both for transporting the
activated
probes from the device for subjecting probes to irradiation in the core of a
nuclear reactor,
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extending into the core of the nuclear reactor to the decay station 330 and
for transporting
non-activated probes from the probe supply system 300 to the device for
subjecting probes
to irradiation in the core of a nuclear reactor, extending into the core of
the nuclear reactor.
The direction of the transport is determined by the direction of pressurized
gas flow through
the diverter 200, which is controlled by the probe drive system 370.
Preferably, the device for subjecting probes to irradiation in the core of a
nuclear
reactor is a device 55 for subjecting probes to irradiation in the core of a
nuclear reactor as
described above with reference to Figures 6 to 8.
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